Switched capacitor DC-DC power converters are known in the art and have previously been applied in various types of portable communication devices. Switched capacitor DC-DC power converters are utilized to convert a DC input voltage from an energy or power source, such as a rechargeable battery, of the portable device into a higher or lower DC output voltage suitable for powering various types of integrated circuits and other active components. Switched capacitor DC-DC power converters possess certain attractive properties compared to their inductor-based counterparts for example a relatively low level of EMI, because there is not stored energy in magnetic fields of inductors. Switched capacitor DC-DC power converters may have small size and high energy conversion efficiency. Different topologies of switched capacitor DC-DC power converters are capable of providing DC voltage step-up (i.e. boost) and DC voltage step-down (i.e. buck) with a topology dependent optimum voltage conversion ratio for example 1:2 or 1:3 step-up conversion and 2:1 and 3:1 step-down conversion.
However, there remains a need in the art to provide switched capacitor DC-DC power converters with improved performance characteristics such as higher power conversion efficiency across a wide range of loads, even less emission of electromagnetic noise, reduced voltage ripple on the DC output voltage, improved source regulation and improved load regulation etc. Switched capacitor DC-DC converters are highly useful for powering various types of portable battery powered devices such as mobile phones and smartphones where compact dimensions typically place severe constraints on size, power conversion efficiency and electromagnetic emissions of the power supply circuitry. Furthermore, magnetic field emissions generated by magnetics/inductor based DC-DC power converters are likely to disturb RF signal receipt and transmission of RF wireless transceivers present in the portable communication device.